Difference Between Butane and Isobutane

Butane vs Isobutane

Organic molecules are molecules consist of carbons. Hydrocarbons are organic molecules, which consist of only carbon and hydrogen atoms. Hydrocarbons can be aromatic or aliphatic. They are mainly divided into few types as alkanes, alkenes, alkynes, cycloalkanes and aromatic hydrocarbons. Hexane and n-hexane are alkanes or otherwise, known as saturated hydrocarbons. They have the highest number of hydrogen atoms, which a molecule can accommodate. All the bonds between carbon atoms and hydrogens are single bonds. Because of that, the bond rotation is allowed between any atoms. They are the simplest type of hydrocarbons. Saturated hydrocarbons have the general formula of CnH2n+2. These conditions slightly differ for the cycloalkanes because they have cyclic structures.


As stated above, butane hydrocarbon is a saturated alkane. It has four carbon atoms; therefore, has the molecular formula of C4H10. Molar mass of butane is 58.12 g mol−1. Melting point of butane is 133-139 K, and the boiling point is 272-274 K. Butane is the common name used to indicate all the molecules with this formula. There are two structural isomers that we can draw to match this formula but, in IUPAC nomenclature, we use butane specifically to indicate unbranched molecule, which is also known as n-butane. It has the following structure.


Other structural isomer is like methylated molecule of propane. It is known as isobutane. Butane is a colorless gas. It can be easily liquefied. The butane gas is highly flammable. Butane is a component of natural gas, and it is produced when gasoline is refined. Upon complete combustion, butane produces carbon dioxide and water. However, if there isn’t enough oxygen gas for the combustion, it produces carbon monoxide and water from partial combustion. Butane is used as a fuel. When producing LP gas, butane is mixed with propane and other hydrocarbons. These are used for cooking purposes at household. It is also used in lighters.


Isobutane is a structural isomer of butane. It has the same molecular formula as butane, but the structural formula is different. It is also known as methylpropane. It has the following structure.


Isobutane has a tertiary carbon, and it is the simplest molecule with a tertiary carbon. Isobutane is a colorless, odorless, transparent gas. Melting point of isobutane is 40-240 K, and the boiling point is 260-264 K. It is mainly used as a refrigerant. Pure form of isobutane is used in refrigerators. Further, it is used as a propellant in aerosol sprays.


What is the difference between Butane and Isobutane?

• Isobutane is a structural isomer of butane.

• Butane is unbranched, and isobutane is branched.

• Both have the same molecular formula, but the structural formula is different.

• Butane has four carbon atoms in the straight chain, whereas isobutane has only three carbon atoms in the straight chain.

• Physical properties of butane and isobutane are different. For example, they have different melting points, boiling points, density, etc.

• Pure isobutane is mainly used as a refrigerant